Spanish Basque composer Andrés Isasi wrote a number of string quartets. Volume 1 of the Isasi Quartet's complete survey for Naxos (8.572463, review) featured the early "no.0", posthumously given the opus number 83, and no.2 from 1920. This second disc - a third has already been recorded - pairs the Third and Fourth, dating from the same period as the Second and Fifth. Only fragments of a Sixth and Seventh survive, the latter of which the yearning Aria in D may be the missing slow movement. The fleeting, jerky Scherzetto in F minor may or may not be flotsam from a larger work; there are few clues as to what that work might have been. The three-movement Third Quartet itself could well be incomplete, opus number notwithstanding, and is labelled as such on the track-list.

Once more, Isasi's wistfully chromatic music sounds much more Germanic (Strauss, Weingartner) than Spanish or Basque, underlining the irony of the 'Spanish Classics' category this disc has been issued under. For the Isasi Quartet only Anna Bohigas and Karsten Dobers are left from the first volume, but the ensemble remains essentially Germanic in outlook. Their name in any case obviously indicates a strong affinity for the composer's music, and indeed there is a glove-like fit - these are all premiere recordings, but it is hard to imagine a more natural, sympathetic reading.

Isasi's big Second Symphony, also highly Teutonic in essence, is also available on Naxos in a surprisingly attractive performance by the Bilbao Symphony Orchestra (8.557584, review). That disc was released a decade ago - meaning that a recording of the First is long overdue! Richard Whitehouse supplied the notes back then and he is still going strong, offering for the present programme illuminating background detail and musicological descriptions of these imaginative, appealing works.

Recorded at the same luxury venue as the first disc, sound quality here is rather bright but good. Happily, the artificial clipping of natural reverberation that slightly marred the first volume has gone.

Isasi has already bowed in as a composer of string quartets with Naxos 8.572463 (Numbers 0 and 2). In what will be a complete edition the Quartet that bears this Spanish composer's name has one further volume to go before all five quartets have been made available on CD. There are seven in all but 6 and 7 were probably unfinished and only fragments remain. Of Number 3 there are only the first three movements. Four of these quartets (2-5) date from 1920-21.

This Bilbao-born composer followed in the musical footsteps of his older brethren, Usandizaga and Guridi, the latter also a string quartet practitioner. Isasi’s Second Symphony has been recorded by Naxos with his native city's symphony orchestra under a conductor whose name is now much more familiar in the UK as Juanjo Mena - a Chandos stalwart.

Isasi’s Fourth Quartet is a work of romantic lyricism. It has no truck with dissonance. Its world grows directly from that of Schubert and Dvořák yet with a richer weave. At times it links arms, all unknowingly, with Bax's String Quartet No. 1 and the Moeran quartets. Its second movement, Romanze, mixes in a degree of Bachian songfulness. After a smiling Scherzo we get a joyous Rondo finale touched with the harmonic density of the first movement. There’s even some of the eerie complexity of the instrumental writing in Warlock's Curlew. It ends in animated fashion but without extreme fireworks. Dignity is the sign-off. Contrast this with Number 3, the first movement of which is flecked with darker material and even tragic tints. Even so the language is very much in keeping with its coeval successor. Another flighty bucolic scherzo precedes the touchingly sentiment-imbued Adagio molto espressivo which for now must serve as a finale.

Then follow what amount to three quartet miniatures: An Aria which has a repose caught delightfully between Bach and Finzi, a huskily flickering Macchiato Scherzetto and a Preludio entitled Jinete de Abril (April Horseman) - becalmed and calming. These pieces date from Spain’s deeply troubled 1930s.